The present invention relates generally to an integrally formed combination of a motor device and a transmission device, having two power inputs and a power output having a continuously variable speed of rotation over a large range. The invention employs novel uses of a differential unit or a planetary gear unit. It is useful for rotating a drive e wheel of an electric vehicle, or as a flywheel unit for power storage and delivery in a conventional vehicle.
It has long been a goal in the art to find a combination power source (i.e., drive) and transmission device that can deliver the peak output of the power source over a large range of the rotational speed (rpm) output of the transmission device. Further, it is preferable that this peak power be output from the transmission device, or from the drive device incorporating the transmission device, at continuously variable speeds of rotation over a large range of the speed of rotation of the output. A transmission device making possible such properties is known in the art as an infinite speed transmission device. The term "drive and transmission device" or "combination motor and drive device" is employed in the present disclosure to describe the case of the device including the drive means (i.e., power source means) as well as the transmission means. The term "motor and transmission device" or "combination motor and transmission device" is employed for the case of the drive means including an electric motor means, as the drive means (i.e., power source).
Known transmission devices typically involve a single rotational mechanical input and a single rotational mechanical output. Such known transmission devices, whether manual or automatic, may typically employ a set of gears. In these transmissions, the ratio of the speed of rotation of the input to the speed of rotation of the output is one of a set of fixed values corresponding to the set of gears. These typically involve a large number of parts, undesirable weight for many applications particularly in vehicle propulsion, and high losses due to multiple transfers of the power between the many components within the transmission device, or within the drive device incorporating the transmission device.
The mechanical rotational input for such known transmission devices can be the output of a gasoline or electric motor, many of which typically have a limited speed (rpm) range for peak power. As a result, the transmission device may not have a continuously variable output rotational speed for the speed of the motor in the peak power range.
The effective range over which the peak power output can be maintained increases with the number of gears in the transmission device, but only in the sense that the range is made up of overlapping sub-ranges, each sub-range being a narrower rpm range over which the peak power is output when the known transmission device is in a respective one of the gears. However, the larger the number of gears, the heavier and more expensive the transmission device becomes, and the less efficient due to the number of interfaces (mechanical links) across which the power must be transferred.
Differential units and planetary gear units are known in the art as transmission devices. The typical use of a differential transmission unit is in a vehicle, to distribute the power from the drive shaft to the pair of drive wheels. In this use the rotational mechanical input of the drive shaft is transmitted by a gear fixed on the end of the drive shaft to a ring gear of the differential transmission unit. The ring gear is attached to a frame which holds a pair of pinion gears to rotate between a pair of drive gears. Each of the drive gears is fixed to a shaft to turn a respective one of the two drive wheels. The two drive gears rotate coaxially, and the output rotates about an axis transverse to the axes of the drive gears.
Rotation of the pair of pinion gears between the drive gears allows the two wheels to rotate independently while both drive the vehicle. The amount of rotation of the pair of pinion gears corresponds to the difference in rotation between the two
drive wheels, such as for going around corners or when one of the drive wheels loses traction.
Known planetary gear types of transmission devices involve an inner sun gear, an outer ring gear and a set of planetary gears held by a hub to rotate between the sun gear and the ring gear. When the sun gear rotates with respect to the ring gear, the planetary gears rotate between them, and the hub rotates accordingly, coaxially with the sun and ring gears.
In a typical prior art use of the planetary gear unit, the hub is fixed, and either the sun gear or the ring gear is driven as the rotational mechanical input, the other providing the rotational mechanical output. Alternatively, either the sun gear or the ring gear can be fixed, the other is either the rotational mechanical input or output, and the hub provides the other of the rotational mechanical input or output.
In the prior art, combinations of a transmission device and an electric motor drive device typically involved use of a separate electric motor, the shaft of which extends to provide a rotational mechanical input to the transmission device. The shaft is typically supported by two bearings at two separated parts of the shaft, the motor elements being located between the positions of the bearings.
The prior art does not involve combining any of the essential elements of the electric motor means integrally with the essential elements of the transmission means, nor the supporting of the element of the electric motor with a single bearing. Thus the prior art arrangements for combined motor and transmission means involved a large number of parts and an undesirable associated weight.